Increased SK3 expression in DM1 lens cells leads to impaired growth through a greater calcium-induced fragility
| Autor: | Jeremy D. Rhodes, John P. McAbney, Alan R. Prescott, Darren G. Monckton, George Duncan |
|---|---|
| Rok vydání: | 2006 |
| Předmět: |
Adult
musculoskeletal diseases congenital hereditary and neonatal diseases and abnormalities Programmed cell death Cell Survival Small-Conductance Calcium-Activated Potassium Channels Blotting Western Biology Apamin Polymerase Chain Reaction Cataract Ouabain Cell Line chemistry.chemical_compound SK3 Lactate dehydrogenase Lens Crystalline Genetics medicine Humans Myotonic Dystrophy Molecular Biology Genetics (clinical) Aged Cell Proliferation Homeodomain Proteins Cell growth Epithelial Cells General Medicine Middle Aged Molecular biology Kinetics chemistry Biochemistry Cell culture Ionomycin Potassium Calcium Trinucleotide Repeat Expansion medicine.drug |
| Zdroj: | Human Molecular Genetics. 15:3559-3568 |
| ISSN: | 1460-2083 0964-6906 |
| DOI: | 10.1093/hmg/ddl432 |
| Popis: | Although cataract is a characteristic feature of myotonic dystrophy type 1 (DM1), little is known of the underlying mechanisms. We generated four lens epithelial cell lines derived from DM1 cataracts and two from age-matched, non-DM cataracts. Small-pool PCR revealed typical large triplet repeat expansions in the DM1 cells. Furthermore, real-time PCR analysis showed reduced SIX5 expression and increased expression of the Ca(2+)-activated K(+) channel SK3 in the DM1 cells. These cells also exhibited longer population doubling times which did not arise through reduced proliferation, but rather increased cell death as shown by increased release of lactate dehydrogenase (LDH). Using (86)Rb(+) as a tracer for K(+), we found no difference in the resting K(+) influx or efflux kinetics. In all cases, the ouabain sensitive component of the influx contributed approximately 50% of the total. However, stimulating internal Ca(2+) by exposure to ionomycin not only caused greater stimulation of K(+) ((86)Rb) efflux in the DM1 cells but also induced a higher rate of cell death (LDH assay). Since both the hyper-stimulation of K(+) efflux and cell death were reduced by the highly specific SK inhibitor apamin, we suggest that increased expression of SK3 has a critical role in the increased Ca(2+)-induced fragility in DM1 cells. The present data, therefore, both help explain the lower epithelial cell density previously observed in DM1 cataracts and provide general insights into mechanisms underlying the fragility of other DM1-affected tissues. |
| Databáze: | OpenAIRE |
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